Isolation and Structure of Human Histocompatibility (HLA) Antigens

Abstract

Histocompatibility (transplantation) antigens were initially described as being responsible for the rejection of tumor and tissue grafts between nonsyngeneic individuals (Gorer, 1938; Snell, 1948). Genetic analyses subsequently established that the major transplantation antigens are the products of genes located at two separate, but closely linked, loci. More recent studies have indicated that these loci delineate a chromosomal region that controls a complex series of cell-mediated reactions. This region is referred to as the major histocompatibility complex.: In mice, it is denoted as H-2;: in humans, as HLA.: The H-2: complex has been more extensively studied than the analogous human region, and many of the functions of the HLA: complex are based on analogies with the mouse data. The exact number of genes present in each complex is not known, although most workers are agreed that the number is large. Thus, for example, Klein (1975) has suggested that the H-2: complex contains sufficient DNA to code for up to 2000 polypeptide chains, each of about 200 amino acids. The relationships among the genes have not been established, but their functions appear to be related and to be primarily concerned with the control of expression of cell-surface antigenic determinants, immune-response differences, certain complement functions, and probably other functions related to cell-cell recognition.